The invention relates to a steering shaft anti-theft device for a motor vehicle, of the type comprising a lock bolt interacting with at least one radial hollowed-out part of a sleeve integral with or fixed to the steering shaft.
Anti-theft devices of the aforementioned type have performed their function satisfactorily for a number of decades but nevertheless suffer from various drawbacks or prove inconvenient in use. In the first place, since the bolt is practically never situated opposite a hollowed-out portion of the sleeve, so that a restoring spring has to be provided for the bolt, rendering the construction complicated and fragile, and the user has to turn the steering wheel, with the vehicle stationary and the engine shut off, in order to cause the bolt to engage. This operation, which the user often forgets to perform, involves considerable effort, particularly when the steering equipment includes a power steering auxiliary device, which is inoperative when the engine is not running.
Furthermore, to release the steering a torque often has to be applied to the steering wheel and may have to be quite considerable if a wheel is resting against the curb. In addition, these known systems, are not suitable for the control of the bolt by means of an electrical, pneumatic or hydraulic device, particularly owing to the unlocking force often required.
Efforts have therefore been made to replace the anti-theft devices of the foregoing type by means to ensure the locking of the steering shaft in all positions. The devices proposed, however, are imperfect and/or complicated, so that the demand for them is limited.